Stand-alone system presizing

Presizing is a rough estimation of PV system energy yield and whether user needs are met, based on a few general parameters. Its purpose is to determine the optimal PV array power and battery pack capacity required to meet user needs.

Input solar energy is computed in monthly values (accounting for plane orientation and horizon) using only the monthly data from the "Sites" database.

Besides battery voltage—which relates to overall system power and geographic extension (due to distribution ohmic losses)—the two basic user parameters are:

• The desired system autonomy (in days), which determines the battery capacity.
• The required "Loss of Load" (LOL), giving the required PV array nominal power.

After sizing the PV system with this tool, its real performances should be verified by performing a detailed simulation (option "Project design"), using real components and taking all system perturbations into account.